1.) Stealth Device - The stealth device is removed when your ship takes a hit. Is the device removed when you take damage from an asteroid? I'm sure its been talked about previously, but I couldn't find it. There was some talk in other topics about damage not being caused but a hit (results of rolling attack dice from a ships attempt to shoot you) and damage taken. This damage does occur after rolling an attack die, but can the dame an asteroid does be considered an attack?

2.) Advanced Cloaking Device - after you perform an attack, you may perform a free cloak action. How is performing an attack defined? Does there need to be an enemy in range and in arc and you roll dice trying to damage. Or can you fire your weapons in to the darkness with no target if there are none available?

3.) Decloaking action - can you pre measure and then decide which maneuver to use, or do you have to commit to one of the 3 (or 6 for Echo) and then try to do it and if unable, then being unable to decloak?

1) No. The only way to lose the Stealth Device is to be hit by an attack. If there's no attack, there's no hit and the Device stays.

2) You have to perform an attack. Attacks require a target.

3) A regular decloak works much like a barrel roll. You pick the direction you wish to move in, and if you can pull it off then you must. If you can't pull it off, then you may choose a different direction or you can choose not to decloak at all. No pre-measuring.

Echo is a little bit trickier. I think it works on the same principle (pick a direction, if you can do it you're committed, otherwise you can choose again), but I don't know how the bank template works with that (is right-forward a direction, or do you just pick "right" and flip the template as needed?).

DR4CO is right on target with his answers.

The issue of Echo's unique decloak move and what exactly counts as a "direction" has been discussed at great length here:

http://community.fantasyflightgames.com/index.php?/topic/108883-spending-the-decloack-token-decloaking/?view=findpost&p=1127917&hl=%2Becho+%2Bdecloak

And also here:

http://community.fantasyflightgames.com/index.php?/topic/108145-echo-de-cloak-template/?hl=%2Becho+%2Bdecloak

I believe the conclusion was that each orientation of the template counts as it's own direction for the purpose of declaring a move. For example; if you declare a forward right bank for Echo's decloak move but are unable to complete the maneuver, you are not forced to move forward left instead. You may choose to declare a different direction, or choose not to decloak at all.

This is similar to Lt. Lorrir's barrel roll, but the wording of the cloak rules caused confusion for some. For reference, Lorrir's ability is discussed here:

http://community.fantasyflightgames.com/index.php?/topic/108975-lt-lorrir/?view=findpost&p=1126519&hl=%2Becho+%2Bdecloak

Judging from your questions I assume you're learning to fly a Phantom. Good luck & happy hunting!